SIRIUS 3RA2 non-fused motor starter — direct starter, S0 frame
The Siemens 3RA2125-1HA24-0AP6 is a SIRIUS non-fused motor starter in the 3RA2 family, configured as a direct starter (across-the-line) in the S0 size. It integrates a 3RT2024-1AP60 contactor and a thermal bimetallic overload relay into a single unit, saving panel space and wiring compared to a contactor-plus-relay build.
Overload protection and contactor pairing — Class 10, bimetallic
This is the correct class for most general-purpose motor starting; a Class 20 would allow longer locked-rotor time but risks winding damage on frequent starts. The supplied contactor (3RT2024-1AP60) is already wired to the overload block via the link module 3RA2921-1AA00, so the starter arrives as a single assembly. Main contact wiring accepts 1–10 mm² stranded, or 2×(2.5–6 mm²) for paralleled feeds.
Panel integration — DIN rail snap-on, S0/S00 footprint
Mounts vertically on a DIN rail via snap-on fastening, or can be screw-mounted with an additional push-in lug. The S0 size (45 mm wide, 97.1 mm deep, 193.1 mm high) fits standard 45 mm slot spacing; the circuit-breaker portion is S00 size, so the overall depth is driven by the contactor and overload block. Clearance requirements: 30 mm upward, 10 mm forward, 10 mm downward, 9 mm at the side, and 0 mm backward — the back is flush to the mounting surface. These are the minimum air gaps for heat dissipation and arc flash clearance; a panel builder should maintain them, especially when grouping multiple starters side-by-side.